The prevalence of depression among people with co morbid medical illness is 3 to 5 times higher than in the general population. Among people with chronic medical illnesses, depression is associated with excessive morbidity and premature mortality. Few studies have examined the detection and treatment of depression in this population. The goal of this research is to examine the quality of depression care for people with coincident chronic medical illness. Using cross-sectional and longitudinal data from a national survey, the proposed research will estimate (1) the likelihood of case identification of people with chronic illness and depression and (2) the impact of chronic medical illness on the use, type, and quality of mental health services for people with depression, and (3) examine effects of depression treatment on medical and social outcomes among people with co morbid depression and chronic medical illness. The results of the proposed research will be useful to health care providers and policymakers dedicated to improving the quality of mental health care. Understanding better the quality of depression care for this population and determining the potential effects of depression treatment can inform future policies and research directions. [unreadable] [unreadable]